"In process" cleaners are employed in the metal treatment industry to clean and passivate a metal surface. These types of aqueous cleaners are typically based on organic rust-proofing or passivating agents such as combinations of alkanolamines and fatty acids, surfactants, anti-foam agents and/or phosphonates and possibly biocides and builders. In order to passivate a metal surface to prevent rusting during process breaks and storage, appropriate additives are used. Cleaning and passivating agents which inhibit the corrosion of ferrous metal surfaces contain for example alkali nitrites, alkanolamines, soaps and benzoates.
Clean and passivate treatments are typically employed in applications which require good cleaning and temporary metal passivation during exposure to the atmosphere. Treated parts may need to remain rust-free, while exposed in the manufacturing plant for from several hours up to 30 days. In order to maintain their rust prevention ability, these cleaners are not rinsed. Current commercial cleaners typically employ alkanolamines such as monoethanolamine, diethanolamine or triethanolamine as a passivating agent for ferrous surfaces. The alkanolamine component inhibits flash rusting of ferrous iron parts during line stops or storage. Typical cleaners also will include surfactants such as glycol ether compounds and phosphonate compounds which aid in cleaning of the parts. For example, U.S. Pat. No. 4,578,208 which issued to Geke et al. discloses a cleaning and/or passivating composition and process which employs a phosphoric acid ester, an alkanolamine and a surfactant and optionally builders, non-ferrous metal inhibitors and biocides.
Currently, environmental objections are being raised concerning the use of alkanolamines, phosphates and glycol ethers as raw materials for industrial processes.